Supplemental Oil and Natural Gas Information - Summary of Costs Incurred in Oil and Natural Gas Properties (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquisition costs:
Unproved properties	$ 57,498	$ 24,764	$ 24,722
Development cost	257,119	150,778	259,655
Exploration cost	18,791	20,127	20,530
Total acquisition, development and exploration costs	$ 333,408	$ 195,669	$ 304,907

Costs (benefits) incurred acquisition of unproved oil and gas properties.

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- References

No definition available.

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- Definition

Development costs incurred, including capitalized costs and costs charged to expense, in oil and gas activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 18
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62014-109447

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- Definition

Exploration costs incurred, including capitalized costs and costs charged to expense, in oil and gas activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 18
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62014-109447

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- Definition

Amount of costs incurred related to oil and gas property acquisition, exploration and development activities, including capitalized costs and costs charged to expense.

+ References

No definition available.

+ Details

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